Rotary pump.



R. H. NESMITH. ROTARY PUMP.

APPLICATION FILED SEPT. 18, 1912.

1,096,186, Patented May 12,1914,

2 SHEETS-SHEET 1.

iwi/humus 3 Wue W606 R. H. NESMITH.

ROTARY PUMP.

APPLICATION FILED SEPT. 18, 1912.

1,096, 186, Patented May12,1914.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

RALPH H. NESMITH, 0F Ell-MIRA, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS,T0 AMERICAN-LA FRANCE FIRE ENGINE COMPANY, INC., CORPORATION OF NEWYORK.

ROTARY PUMP.

Specification of Letters Patent.

Patented May 12, 1914.

chamber on one side of the line of centersof said gears and a dischargechamber on the other side of said line of centers.

The primary object of this invention is to provide an improvedconstruction, combination and arrangement of parts according to which adevice of this character can be simply and durably made and renderedefficient in operation.

Toward the attainment of this object, my invention contemplates theprovision of suitable partitions or fixed vanes for shielding the rotarygear elements from the direct pressure of the in-rushing fluid in adirection retarding the movement of said gears.

A further object is to dispose these vanes and partitions in such amanner as will direct the in-rushing fluid against said gears in adirection to reinforce their movement.

Another object is to provide an improved by-pass for releasing the fluidwhich becomes pocketed between the intermshing teeth of the gears on thedelivery side of the pump and which by-pass will deliver such fluid intothe main-current which leaves the ump.

Other collateral objects will appear in the specification and bespecifically pointed out in the appended claims, reference being had tothe accompanying drawings exemplifying the invention and in which-Figure l is a vertical section of a pump constructed in accordance withthe principles of the present invention, parts being shown in elevation.Fig. 2 is a top plan view of the same, parts being broken away and partsshown in section. Fig. 3 is a section on the line III-III, Fig. 1,looking in the direction of the arrows. Fig. 4 is an inside face view ofone of the covers detached.

Referring more particularly to the drawings and to the embodiment showntherein,

the rotary pumping elements comprise a smaller gear 1 and a larger gear2, suitably mounted within a housing 3, which housing is provided withthe inlet chamber 4 and the delivery chamber 5. A partition wall 6 isprovided in the housing 3 to conform with the periphery of the gear 1for a portion of its circumference, while a like partition 7 "issimilarly disposed about gear 2, said partitions being adapted to formwith the gear teeth 8 and each of said gears, of fluid holding cells 9.

The gears 1 and 2 are rotatable in the directions shown by the arrows inFig. 1. Upon opposite sides of the gears 1 and 2, the housing 3 isprovided with intake openings or passages 10 and 11, such intakes beingcommonly disposed in this manner in fire engines embodying pumps of thischaracter, so as to adapt the fire engine to be comected up with a waterplug from either 51 e. rangement has heretofore been that waterdelivered through the intakes l0 and 11 under any considerable pressure,has been projected against the pumping gears 1 and 2 in a direction toretard theirmovement. Insome instances the pressure of the inflowingwater has been sufficient to render the pump inoperative by stallingsaid gears. In order to obviate these difliculties, the partitions 6 and7 are, according to the present invention, provided with the fixed vanesor extensions 12 and 13 respectively, which serve to deflect theinfiowing water away from those portions of the gears 1 and 2, which aremoving in a direction contrary to the fiow of the inflowing water.Further-- more, said extensions 12 and 13 are suitably arranged toconfine the current from either inlet, to a channel which delivers theinrushing water to one or the other of said gears 1 and 2 at theperiphery thereof and in the direction in which it is moving, thusimparting the momentum of the pressure driven water to the gears in themost effective manner. For this purpose, partitions or vanes 12 and 13have their extremities deflected outwardly away from the gears. 1 and 2in such a way as to form raceways which contract in the direction ofrotation of said gears. To enhance this effect, the wall of housing 3 isrovided with a rounded protuberance 3' intermediately of the inlets 10and 11 which causes the infiowing water a plurality One of the drawbacksto this aragainst the teeth of the opposite gear in a directiontangential to the path of movement of said teeth. Further diflicultieshave been encountered in pumps of this character by reason of eddycurrents created in the delivery chamber 5,'the operation of the pumpbeing seriously interfered with on this account. the partition 6 isprovided with a smaller extension or vane 14 which is deflected up-.wardly from-the gear 1 and a similar larger partition or vane 15 whichoverhangs the larger gear 2. A discharge port 16 is formed-between theadjacent extremities of the upper extensions 14 and 15, the extension 15being cut away at 18, as shown best in Fig. 2 to equalize thedistribution of fluid discharged at either side of the chamber 5. One ofthe difliculties that has heretofore been encountered in pumps of thischaracter is a greatly reduced capacity by reason of a considerableportion of the discharge fluid becoming pocketed between intermeshingteeth of the gears 1 and 2, the result being that considerablequantities of water has been returned to the suction chamber 4 insteadof being discharged upwardly into the outer chamber 5. To overcome thisdifliculty the present invention contemplates the provision of a vent orby-pass 19 in either or bothof the covers 20 of the housing 3. By aninspection of Figs. 1 and 3 it will be seen that the water thus pocketedwill be dis placed laterally into the by-passes 19 and upwardly into thechamber 5. In order to facilitate as far as possible the action of theby-passes 19, said by-passes are made deepest adjacent the line ofcenters of gears 1 and 2 and made shallower toward the discharge port 16being flared upwardly to permit the return of the'entrapped fluid to theoutgoing currents with a minimum degree of back 1 pressure. ,The gears 1and'2 are preferably journaled in bearings 21 which are carried by thecovers 20 on the housing 3.

It is obvious that only a'very small clearance should be allowed betweenthe faces of the gears and the adjoining heads of the casin in order toprevent water from slipping i361! from the discharge into the suctionside of the pump. In order to prevent undue friction between the gearwheel faces and the casing walls when the gears are closely fitted(allowing about 0.002" play on each side) I provide means by which thegears are maintained laterally centered with the proper clearance oneach side as above stated. These means constitute slight pockets orrecesses 25, 25 Fig. 1 provided in each face of each gear, as close totheir periphery and in as many rows as possible. These recesses, whenrunning over or past by-pass 19, are filled with fluid of the samepressure, which prevails on the discharge To overcome thesedifliculties,

side of the pump. Their tendency to dischargethe fluid during theremainder of their travel, where the fluid pressure in the adjoiningcells 9 is low, maintains on each side of the gears a film of fluidbetween their faces and the casing heads which most effectively preventsthe gears from touching the casing heads, and thus prevents undue wearat these points of the pump. It is of course obvious that these recessesor pockets may have any suitable shape. I prefer to make them round asshown, as the cheapest way of manufacturing. Also the pockets 25arranged in one or more rings as shown in Fig. 1 act as an effectivemeans for preventing the water to slip past the gear wheel faces fromthe discharge to the suction side.

The operation of the several parts of my improved pump engine has beensuificiently. indicated in the description embodied in the foregoingspecification.

What I claim is 1. In a rotary pump, a pair of rotary elements providedwith cooperating periphcries, a housin for said rotary elements, saidhousing being provided with inlet passages extending toward each otheraround portions of the peripheries of said rotary elementsrespectively,the wall of said housing intermediate to said inlet passages, beingsuitably formed to direct the inflowing water under pressure from eachof said passages to the opposite rotary element in a directioncorresponding to the direction of movement of that portion of the rotaryelement which is struck by the inrushing water.

2. In a rotary pump, a rotor housing provided with inlet and dischargepassages, and a rotor in said housing, said housing being provided withan intake for water adjacent a portion of said rotor which is moving ina direction contrary to the flow of water through said intake, and apartition interposed between the intake and said rotor, said partitionbeing deflected away from said rotor to format gradually contractedpassageway for directing the water'against said rotor only in thedirection of movement of that portion of said rotor which is adjacent tosaid intake.

3. In a rotary pump, a pair of rotaryelements provided with cooperatingperiphcries, a housing for said rotary elements, said housing beingprovided with inlet passages extending toward each other around portionsof the peripheries of said rotary element-s respectively and adapted bythe con formation of said housing to direct the insages, saidprotuberance being adapted to deflect the inrushing water toward therotary element opposite to the inlet from which the inrushing watercomes, and partitions extending'around portions of the peripheries ofsaid rotary elements and toward said protuberance on the inner wall ofsaid housing.

said passages to the opposite rotary element in a directioncorresponding to the direction of movement of that portion of the rotaryelement which is struck by the inrushing water, a protuberance on theinner wall of said housing intermediate of said inlet passages, saidprotuberance being adapted to deflect the inrushing water toward therotary element opposite to the inlet from which "the inrushing watercomes, and partitions extending'around portions of the peripheries ofsaid rotary elements and toward said protuberance on the inner wall ofsaid housing, said partitions being deflected away from the peripheriesof said rotary elements 'to bring them into approximate conformationwith the Wall of said housing on the other side of said protuberance.

,5. In a rotary pump, a pair of intermeshing toothed pumping elementsand a housing conforming approximately with the peripheries of. saidpumping elements on the olfsides thereof to form fluid transportingcells between adjacent teeth and having ex tensions overreaching saidpumplng elements and spaced from the outer walls of said housing toprovide guide vanes for directing fluid under pressure against saidelements in the' -direction of rotation only, said extensions beingadapted to form portions of the walls of said inlet passages.

6. A gear pump comprising a pair of intermeshing gears and a housingforming inlet and discharge chambers on opposite sides of the lineof'centers of said gears, said housing being provided.w'ith curvedwalls' conforming to said gears, extensions on said curved wallsprojecting inwardly toward each other to provide fluid controllingports,

and a by-pass extending 'from approxi- -mately the line of centerstoward theport of discharge side of said pump.

7. A ear pump comprising a pairof i'ntermes ng gears and ahouslng'forming inlet and discharge chambers on opposite-sides of theline of centers of saidgear s, said housing being provided with curvedwalls conforming to said gears, extensions on said curved wallsp-ro]ectin inwardly toward each other -to provide fluidcontrollingports,

and a by pass extending from approximately the line of centers towardthe port on the discharge side of said pump, saidv extensions havingtheir extremities deflected away from the peripheries of said gears.

8'. A gear pump comprising a pair of intermeshing gears-and a housingforming inlet and discharge chambers on opposite sides of the line ofcenters of said gears, said housing being-provided with curved walls,conforming to sald gears, extenslons on said curved walls projectininwardly toward each other to provide fluid controlling ports,

and a by-pass extending from approximately the line of centers towardthe port on the discharge side of said pump, said by- V pass beingflared toward said discharge port.

9. A gear pump comp-rising inter-meshing pumping elements, a housingtherefor provided with intakes directed opposite to the direction ofrotation of said pumping ele-' 'ments, said intakes being respectivelyadapted to deliver fluid to the pumping elements disposed oppositelythereto, and oppositely disposed partitions respectively shielding saidrotary elements from the retarding pressure of fluid entering saidintakes.

1Q A gear pump comprising 'intermeshing pumping elements, a housingtherefor provided with intakes directed, opposite to the direction ofrotation of said pumping elements, oppositely disposed partitions re-'spctively shielding said rotary elements A from the retarding pressureof fluid entering saidintakes, and other partitions arranged on thedelivery side of said pump for preventing the return of fluid to said v,11. A gear pump comprising intermeshing pumping elements, a housingtherefor provided with intakes respectively directed opposite to thedirection'of rotation of said pumping elements, oppositely disposedpartitions respectively shielding said rotary ele ments from the.retarding pressure of'fluid' entering said intakes, and other partitionsarranged on the delivery side of'said pump for preventing the return offluid'to said pump, said other partitions having their ex-f tremitiesdeflected away from said pumping elements to form a discharge port; 7 v

RALPH NESMITH. Witnesses H. JAUBE, WM. Co 'n'rnANor

